How did the leaks spread?

The hashtag #MacronLeaks appeared on Twitter on an account used by a US alt-right figure on Friday afternoon - and was reportedly retweeted 87 times in the first five minutes, suggesting the use of automated bots to spread the information faster.

Within 90 minutes, the information had caught the attention of prominent supporters of Marine Le Pen and was further spread by bots.

Some three-and-a-half hours after the initial tweet, #MacronLeaks had been used some 47,000 times and the prominent Wikileaks account played a key role in publicising the hashtag.

Who might be responsible?

That too remains unclear. The Macron camp has not blamed any specific party but said the hack clearly aimed to damage it and undermine French democracy,

It compared it to the leak of Democratic Party emails in last year's US presidential election that was blamed on Russian hackers.

Wikileaks, which published those emails, posted a link to the Macron documents on Twitter but implied it was not responsible.

Is this unprecedented?

Mr Macron's team has already been the victim of hacking attacks, for which it has blamed groups based in Russia and Ukraine. It suspects the Kremlin of wanting to help Ms Le Pen, who supports a pro-Moscow foreign policy.

Macron campaign servers went down for several minutes in February after attacks apparently originating in Ukraine

Last month security experts from the company Trend Micro said that Russian hackers were targeting Mr Macron's campaign, using phishing emails, malware and fake net domains in an attempt to grab login names, passwords and other credentials of campaign staff

Russia has denied that it is behind attacks aimed at Mr Macron.

On Thursday, the centrist candidate filed a lawsuit over online rumours that he had a secret bank account in the Caribbean.

Mr Macron called the allegations "fake news and lies" and said some of the sites spreading them were "linked to Russian interests".

Sunday, 14 May, marks the end of outgoing President François Hollande's term, and is the latest possible date for the inauguration and official transfer of power to his successor.

BBC coverage

You can follow the French election on the BBC News website. Click here for all our latest stories.

On the day of the election, we will be running a live page bringing together the latest news, video and analysis.

On TV, you can watch a BBC World News Election Special, from 18:30 BST (17:30 GMT / 19:30 local time in France) on Sunday, which will be broadcast on BBC News in the UK and on BBC World News internationally, with Christian Fraser presenting from Paris.

For radio, BBC World Service will broadcast a special extended edition of Newshour from Paris at 18:00 GMT on Sunday.